(2^4*7^3)/(7*2)^2= (2^4*7^3)/7^2*2^2=2^2*7^1=4*7=28
(7^7*2^5)/14^5=(7^7*2^5)/(7*2)^5=(7^7*2^5)/7^5*2^5=7^2=49
(3^7*4^4)/12^4=(3^7*4^4)/(3*4)^4=(3^7*4^4)/(3^4*4^4)=3^3=27
Х²+10х+16≥0
D=100-64=36; √D=6
x1=(-10+6)/2=-2
x2=(-10-6)/2=-8
+ \ - / +
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-8 -2
Ответ: при х € (-∞ ; -8] U [-2 ; +∞).
Делим обе части на cos^2 x, имеем:
4 tg^2 x - 5 tg x - 6 = 0
tg x = t
4 t ^ 2 - 5 t - 6 = 0
D = 25 + 96 = 121
t = (5 +- 11) / 8
t1 = 2 t2 = - 3/4
tg x = 2 tg x = -3/4
x = arctg 2 + πn x = arctg (-3/4) + πn
3x - y =7 *3 9x - 3y = 21
2x + 3y = 1 2x + 3y = 1
11x = 22
x= 2
3*2 - y = 7
- y = 7 - 6
- y = 1
y = - 1
Ответ: ( 2; - 1)